I looked into it and apparantly ther are fault codes that will be supplied through can bus. it has to do with interactions with tripping the fan
here is some of the bad news i got
Chris

So far I have this to offer.

Both Webasto USA and Webasto Germany tell me that interfacing the BlueHeat with the RR HVAC will cause check engine light to be posted. They are suggesting you install the generic unit without interface which will mean the loss of the defrost feature. Frankly I am not done yet. I have sent an email to a contact I have at Webasto UK for an other opinion so I am hoping for more info today. Furthermore I am going to get the wiring diagram for your truck from our local LR dealer to see if we can find a way to make it all work for you.

Dennis